Securing of rail-chairs to sleepers



A. C. CLOW SECURING 0F RAIL-CHAIRS TO SLEEPERS June 13, 1939.

Filed Sept. 29, 1937 Ffa. v/.

Patented June 13, 1939 Y PATENT ortica SECURING F RAIL-CHAIRSy TO SLEEPEBS.

Alfred Cecil Glow, Greenwich,` London, England, assignor to Noel Phillips, Emmer Green, near Reading, England Application September 29, y1937, Serial No. 166,458 In Great Britain October 12, '1936 2 Claims.

This invention relates to the securing of railchairs tosleepersandr-isrconcerned especially, though not exclusively, with the re-bushing of the holes in wooden or concrete railway sleepers to provide a firm hold for the chair-securing screws after these have worked loose due to shrinkage and/or decay of the wood, the stripping of the threads in the walls of the holes or like causes.

'Ihe object of the present invention is the provision of an improved method facilitating the securing of the chair-securing screws in a rapid, simple and effective manner.

The method of securing a rail-chair to a sleeper according to the invention comprises the steps of filling a hole in the sleeper with a plug, which consists of a plastic mass capable of hardening to a solid non-plastic mass, forming a screw-threaded bore in the plug while this is still plastic to present a thread of substantially the same pitch and external Adiameter as but of greater depth than that of a chair-securing screw, and screwing a chair-securing screw into the said bore prior to the hardening of the plug.

Various examples of ways in which the method of the invention may be carried into effect and of means to be employed will now be briefly described with reference to the accompanying drawing, in which:

Figs. 1, 2 and 3 are vertical sections illustrating stages in the performance of a preferred form of execution of the method of the inven tion, and

Fig. 4 isa similar view illustrating, in particular, a modied form of tool.

According to the preferred form of the method of the invention, the hole I in a railway sleeper 2 left by the removal of a chair-securing screw which is no longer effective is filled with a plastic mass 3 capable of hardening to a solid mass and the llingis tamped down with a heavy rammer to the level of the surface of the sleeper (Fig. 1). A suitable plastic mass is a moistened mixture of asbestos fibres, advantageously long fibres (about 3" or so in length), and cement, with or without iilling materials such aspumice powf der or the like. Other plastic compositions may, however, beA used, for example, fibres such as asbestos mixed with a yheated bitumen or highmelting point pitch.

The plugged hole is then pierced axially by means of a tool 4 (Fig. 2)r comprising an operative end portion of substantially the same shape as a chair-securing screw. The tool has a screwthread 5, which is of the same pitch (and preferably of substantially the same external diameter) Yas thatl ofthe screw, and` a downwardly tapering core 6 which is of slightly smaller diameter at its upper end than the core at the screw, so that the depth of the thread on the tool, i. e., the dimension a, is greater than that on the screw throughout its length. It is preferred that the depth of the thread on the tool increase in the downward direction although the thread may be of substantially constant depth throughout as shown in Fig. 2. The summit of the thread on the tool is slightly rounded and preferably polished, the nal turn l of the thread near the point 8 of the tool diminishing in height from the maximum to zero in, approximately, half the pitch length. The tool-point 8 is tapered to produce a sharp end projecting beyond the final turn of the thread. The length of the thread is preferably slightly greater than that of the thread of the chair-securing screw. Above the threaded portion, the tool has a shank portion 9 which may be of slightly smallerV diameter than the shank of the chair-securing screw, a collar I0 and a squared head Il or the like by means of which the tool may be rotated about its aXiS;

When the tool 4 has been screwed into the plugged hole I to an extent bringing the upper end of its threaded portion to about the position to be occupied by the upper end of the threaded portion of the chair-securing screw (which position is indicated by contact of the collar Ill with the chair I2), it is unscrewed to leave a moulded thread in the plastic mass of the same pitch as that of the screw but of slightly smaller minimum diameter, the depth of the thread preferably increasing lin the downward direction.

The maximum diameter of the moulded thread is also slightly smaller on account of the rounding of the summit of the tool-thread and may decrease in the downward direction as illustrated in Fig. 3.

The rail-chair securing` screw I3 (Fig. 3) is then screwed home in the screw-threaded bore I4 thus produced. The blunt endl I5 of the screw loccasions nol diiculty since it may readily be A good keying is thus obfacilitate the formation of the threaded bore in the mass.

In some cases, as illustrated in Fig. 4, the tool may be bored axially to accommodate a piercing implement I6 with a head II whereby it is adapted to be driven into the plastic mass or plug prior to the tool proper. Fig. 4 also shows, incidentally, how 'a box-Spanner I8 with a tommy-bar I9 is applied to the squared head I I. The head I'I of the piercing implement I8 enters a recess 2U in the Spanner.

The wall of the hole I in the sleeper may have a groove or thread cut therein prior to the insertion of the plug 3. Such a groove is shown at 2l' in Fig. 4. The expanded plug-material is forced into the groove and enhances the keying effect. The hole I may also have a larger diameter at or near the bottom than the diameter at or near the top.

The method according to the invention has the great advantage that a loose screw may be re-l moved and all subsequent steps eiected for replacing the screw as a tight t without the railchair I2 being displaced or disturbed in any way.

What I claim is:

1. A method of securing rail-chairs to sleepers comprising the steps of filling the entire crosssection of a hole in the sleeper with a non-metallic mass in a plastic state which is capable of hardening to a solid non-plastic mass, tamping the plastic mass in place, forming a screw-threaded bore in the mass in the hole while still plastic to present a thread of substantially the same pitch and external diameter as but of greater radial depth than that of a chair-securing screw and screwing a chair-securing screw into the said bore prior to the hardening of the mass to its non-plastic state.

2. A modification of the method according to claim 1, including the step of forming the screwthreaded bore with a thread increasing in radial depth towards the bottom of the hole.

ALFRED CECIL CLOW. 

